Robert,
An idea from a non-expert (list join in at any time):
As you know, the carbon is caused by oil, which in that location I would
guess would be caused by either bad rings, or bad valve stem seals. With
rings, you'd see blue smoke all the time, with seals, you'd see a puff of
blue out the tailpipe on startup. On the back side of the valve like that,
I'd guess that when you shut the engine down hot, some oil is leaking past
the seal and coking on the back side of the valve, hence the puff at
startup. Since the backside of the exhaust valves are hotter, the problem
would manifest itself there first.
Just a theory, but I'd check the seals.
Good luck,
Ron
----------
> From: robert weeks <robert@woozy.com>
> To: spridgets@autox.team.net
> Subject: mystery valve buildup
> Date: Monday, April 06, 1998 5:16 AM
>
> Hello,
>
> I posted two photos of the head off my engine at:
>
> http://www.woozy.com/midget/head.html
>
> There is an incrediable amount of buildup on the exhaust
> valves for an head that only has 5-6 thousand miles on it.
> The rattling sound that we thought was either a loose
> seat or a bad bigend bearing was actually the crud on the
> backside of exhaust valve #4 hitting the air injector.
>
> If anyone has any ideas on how to avoid or lessen this
> buildup I'd appreciate hearing from them. Maybe a
> different gas or spark plug? There are more details
> on that page as to the gas I've been using, etc.
>
> Thanks,
>
> Robert Weeks
> Durham NC
> 1969 Midget
> http://www.woozy.com/midget/
>
>
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